Rock drill



. Feb. 15,1949. CURTIS ET AL 2,461,530

ROCK DRILL Fild July 2, 1943 2 Sheets-Sheet 2 n ,5// a 5 fr? r fifin 66212 2 215: 6 Z EJ222192 6 fiawiz'n.

by usual spring-pressed pawls 35 carried by a pawl carrier 36. This pawlcarrier is integrally secured to a spirally grooved rifle bar 31 whichextends forwardly into the rear end of the cylinder bore and engages arifle nut 38 secured within the hammer piston. As the hammer pistonmoves forwardly to effect its working stroke, i. e. to strike a blow onthe tappet 8, the pawls of the carrier slip over the ratchet teeth,thereby permitting unimpeded piston movement. Upon rearward movement ofthe hammer piston, the pawls engage the ratchet teeth to hold the riflebar against rotation so that, due to the spiral groove interlockingconnection, a' rotary motion is imparted to the piston, and this rotarymotion is transmitted to the drill steel through the chuck. As is usualin rock drills of the type disclosed, cleansing liquid may be conductedto the drill steel bore to effect cleansing of the drill hole, and thetube provided for this purpose extends axially from the rear head blockinto the motor cylinder and through the hammer piston and tappet intothe drill steel bore. In distinction from other constructions, the tubeis a close sliding fit for the. openings in the impact member 6 and thestriking block 8. During the drilling operation, the water emerging fromthe drill hole runs down over the'forward portion of the chuck, and the4. chuck sleeve projection M is tapered at 55 (Fig. 5), and the frontedge of the piston surrounding the bore i therein is chamfered orrounded-off at 5% so that during normal operation of the drilling motorthe forward end of the hammer piston and the chuck sleeve projectionnever come into substantial contact, or if contact should occur, itwould be relat-ively slight (see Fig. 2). Thus very little wear of thesurfaces at 51' and 58 occurs during normal operation of the drill.Pressure fluid flowing from the cylinder bore through guard 24 directsthe water and dirt over the chuck housing externally of the chuck. Thetappet 8 is mounted for reciprocatory movement in a bore 40 in the chucksleeve I 9, and the chuck sleeve has a reduced rearwardly proiectingportion 4| having a bore 42 which receives the body of the tappet in themanner shown. The tappet projects rearwardly. from the rear end of thechuck sleeve into a position to be struck by the hammer piston.Surrounding the rearward reduced portion M of the chuck sleeve withinthe driver sleeve i1 is an annular chamber 43 into which the forward endof the hammer piston is adapted to enter during its reciprocation aswill later be explained.

The rear end of the cylinder'bore is closed by a rear head plate 44, andarranged between this headplate and the rear head member 32 is avalvechest d5 having a valve chamber containing a pair of cooperatingrelatively movable fluid distributing valves 46 and 47. Carried by therear head block 33 is a throttle valve 48 which may control the flow ofpressure fluid through a supply passage 49 to the valve chamberinternally of thevalves. Leading from the opposite ends of the valvechamber are fluid supply'passages 56 and 5! for conducting pressurefluid, under the to, to the chamber 43 at the forward end of the hammerpiston from the front end of the cylinder bore through the piston flutesto assist in returning the hammer piston after it delivers its impactblow to the tappet 8. Throwing passages 53 and 5 controlled by thepiston connect the cylinder bore with the valve chamber so that thevalves may be thrown automatically into their different operatingpositions as the hammer piston reciprocates. This valve structure andthe. fluid supply and throwing passages are described in the abovementioned copending application Serial No. 475,782.

The exterigr. of the rearward portion of the the piston flutes to theannular chamber 43 also enters the piston bore 1 at the rear of thechuck sleeve projection so that some cushioning of the piston movementtakes place although comparatively little resistance to the forwardmovement of the piston is present at that time. Should the hammerpistonbe driven forwardly into a more advanced forward position, for instance,in the event the drill steel strikes a pocket, the tappet is drivenforwardly into the chuck sleeve bore as shown in Fig. 3 and the surfaces51 and 58 (Fig. 5) move into, contact, thereby providing a seal andtrapping the fluid in the piston bore to provide a substantial fluidcushion for the piston, thus preventing contact of theforward end of thepiston with the chuck parts. Since during normal operation of thedrilling motor little wear ofthe surfaces 5'! and 58 occurs, arelatively fluidtight seal is provided to prevent substantial fluidleakage from the cushion. Of course, there is no substantial loss of thecushion, both because of the maintained surface contact between theimpact surface 5 and the rear end of the striking block 8, and becausethe close fits around the water tube would prevent serious leakage inthe short times available, in any event. If the drill motor is runwithout a steel, the striking block may move up into contact with theinner end of the chuck bushing, and the forward end of the hammer motorpiston may move forwardly almost into contact with the inner end of thechuck sleeve at its extremes of forward movement, and under thesecircumstances the close fits around the water tube will'safely maintainthe necessary cushion pressure against escape.

As a result of this invention animproved chuck mechanism is-providedhaving a novel arrange ment of parts providing adequate bearingsurfaces; whereby ruggedness and relatively long life of the parts areassured. By the provision of the novel dirt and water guard access offoreign matter to the chuck bearing surfaces is prevented. The improveddrilling motor structure embodying the novel cushioning arrangementdisclosed aflfords'" an improved and extremely effective cushioning ofthe hammer piston. Wear of the. sealing surfaces of the cushion issubstantially form of the same is shown for purposes of illustration andthat the invention may be modified and embodied in various other formswithout deetirsli i m s; .1. z

What we claim as new and desire to secure by 1. In a rock drill, a chuckmechanism for a drill steel comprising a chuck housing, a chuck sleeverotatable in said housing, a chuck member detachably secured to saidsleeve for rotation therewith and adapted to receive the shank of adrill steel, and a dirt and water guard rigidly clamped between saidchuck sleeve and chuck member for rotation therewith and having portionsenclosing the forward portions of said chuck sleeve and said housing.

2. In a rock drill, a chuck mechanism for a drill steel comprising achuck housing, a chuck sleeve rotatable in said housing, a chuck memberde tachably secured to said sleeve for rotation therewith and adapted toreceive the shank of drill steel, and a dirt and water guard rigidlyclamped between said sleeve and chuck member and enclosing the forwardportion of said housing.

3. In a rock drill, a chuck mechanism for a drill steel comprising achuck housing, a chuck sleeve rotatable in said housing, a chuck memberdetachably secured to said sleeve for rotation therewith and adapted toreceive the shank of a drill steel, and a dirt and water guard having anannular flange clamped between said sleeve and chuck member andenclosing the forward porticn of said housing.

4. In a chuck mechanism for percussive rock drills, a driver sleevehaving a reduced forward bore and an enlarged rearward bore, a chucksleeve arranged in said front bore of said driver sleeve and having aportion projecting rearwardly into said rear bore, said chuck sleevehaving a bore, a chuck member secured in said chuck sleeve bore andadapted to receive and support the shank of a drill steel, said chucksleeve bore extending rearwardly of said chuck member, said chuck sleevehaving a reduced portion projecting rearwardly into saidenlargedrearward bore, said rearwardly extending bore of said chuck sleeve andsaid reduced chuck sleeve portion adapted to receive and reciprocablyguide a tappet for transmitting blows to the shank of the drill steel.

5. In a chuck mechanism for percussive rock drills, a driver sleevehaving a bore, a chuck sleeve arranged in said sleeve bore and having abore, a chuck member secured in said chuck sleeve bore and adapted toreceive and support the shank of a drill steel, said chuck sleeve boreextending rearwardly of said chuck member, said chuck sleeve having areduced projection extending rearwardly within said driver sleeve boreand having a reduced bore, said rearwardly extending bore of said chucksleeve and said reduced bore in said rearward projection of said chucksleeve adapted to receive and reciprocably guide a tappet fortransmitting blows to the shank of the drill steel.

6. In a rock drill, a chuck mechanism for a drill steel comprising achuck housing, a chuck sleeve rotatable in said housing and projectingoutwardly from the forward end thereof, a chuck member secured to saidsleeve for rotation therewith and adapted to receive the shank of adrill steel, said chuck member projecting forwardly from said sleeve,and a dirt and water guard enclosing the forward portions of said sleeveand housing, said guard having an inwardly directed annular flangerigidly clamped between the front end of said sleeve and said chuckmember and providing a central opening through which said chuck memberprojects.

7. In a rock drill, a chuck mechanism for a drill steel comprising achuck housing, a chuck sleeve rotatable in said housing andprojectingoutwardly from the forward end thereof; a chuck member securedto said sleeve for rotation therewith and adapted to receive the shankof a drill steel, said chuck member projecting forwardly from saidsieeve, and a dirt and water uard enclosing the forward portions of saidsleeve and housing, said guard rigidly secured between said sleeve andchuck member and having stepped front and rear axial bores, the forwardreduced bore receiving the forward portion of said sleeve and therearward larger bore receiving the forward portion of said housing, andsaid guard having a front central opening of smaller diameter than saidbores and through which said chuck member projects.

8. In a chuck mechanism, a chuck housing, a rotatable chuck sleevejournaled in said housing and projecting forwardly therefrom, a chuckmember secured in said sleeve for rotation therewith and projectingforwardly from said sleeve, and a dirt and water guard enclosing theforward portion of said chuck housing and having an inwardly directedfront annular flange surrounding said chuck member and rigidly clampedbe tween said sleeve and said chuck member, said guard serving toprevent the access of dirt and water to the bearing between said sleeveand chuck housing. 7

9. In a chuck mechanism for percussive rock drills, a driver sleevehaving stepped front and rear axial bores of whichsaid front bore is thesmaller, a chuck sleeve secured in the smaller front bore of said driversleeve, a chuck member secured in said chuck sleeve and adaptedtoreccive and support the shank of a drill steel, said chuck sleevehaving a portion projecting rearwardly into the larger rear bore of saiddriver sleeve and having its outer periphery spaced inwardly from thewalls of the larger bore to provide an annular chamber adapted toreceive the annular front end of a hammer piston, said rearwardiyprojecting portion of said chuck sleeve adapted to receive andreciprocably guide a tappet for transmitting the blows of the hammerpiston to the drill steel shank.

19. A water and dirt guard for rock drills, comprising a circular guardbody having alined stepped bores adapted to surround with a closerunning fit relatively rotatable parts of a rock drill chuck to providea dirt seal, and having at one end an inwardly directed annular flangeadapted to be clamped firmly between relatively adjustable rotatableparts of a drill chuck for rotation therewith.

JOHN C. CURTIS. ELMEPu G. GAR'I'IN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,408,691 Clark Mar. '7, 19221,551,096 Gartin Aug. 25, 1925 1,726,295 Gustafson Aug. 27, 19291.,74i8,021 Katterjohn Feb. 18, 1930 1,940,846 Curtis Dec. 26, 19332,255,423 Huffman Sept. 9, 1941

